In current network architectures it is possible for traffic to pass between interfaces of a single router without being processed by a quality of service (QoS) device. For example, as illustrated in FIG. 1, a message can pass from host 145 to host 155 in wide area network (WAN) 100 without being processed by QoS device 110, which provides quality of service processing to WAN 100. A message generated by host 145 and designated for host 155 is sent through routers 140, 130 and 150 to host 155. Only messages that pass from router 130 to QoS device 110 receive quality of service processing. That is, only messages that pass from router 130 to local area network (LAN) 120 or from LAN 120 to router 130 receive quality of service processing. Thus, the configuration of FIG. 1 cannot guarantee quality of service processing for all messages.
Various solutions have been provided for this problem in the prior art. For example, traffic from router 140 and router 150 can be directed to QoS device 110 by separate links. This solution is expensive and provides limited scalability. Simple Network Management Protocol (SNMP) can be used to communicate between QoS device 110 and router 130 to use excess bandwidth provided by QoS device 110 to provide quality of service processing for messages that otherwise would not received QoS processing. However, this solution typically prioritizes WAN traffic over LAN-to-WAN traffic, which may not be appropriate.
A WAN-based quality of service device can be used. However, the benefits of quality of service devices are significantly reduced when QoS device 110 is deployed on the WAN side of router 130 because the primary congestion point exists from the LAN to the WAN, which is not addressed in this configuration.